Methods for the production of aligned carbon nanotubes and nanostructured material containing the same

ABSTRACT

Disclosed herein is a scaled method for producing substantially aligned carbon nanotubes by depositing onto a continuously moving substrate, (1) a catalyst to initiate and maintain the growth of carbon nanotubes, and (2) a carbon-bearing precursor. Products made from the disclosed method, such as monolayers of substantially aligned carbon nanotubes, and methods of using them are also disclosed.

This application claims the benefit of domestic priority to U.S.Provisional Patent Application No. 60/899,868, filed Feb. 7, 2007, whichis herein incorporated by reference in its entirety.

The present disclosure relates to a continuous or semi-continuous methodfor making high volumes of aligned arrays of surface grown carbonnanotubes. The present disclosure also relates to the use of surfacegrown carbon nanotubes in nanostructured materials by interlinking,fusing, functionalizing, and or weaving them together to form highstrength one, two and three-dimensional materials.

Aligned arrays of carbon nanotubes have many advantages over carbonnanotubes produced from gas phase or from powdered catalyst such as easeof dispersion orientation control, length of millimeters and beyond.Aligned arrays of carbon nanotubes have been produced and arecommercially available, however, due to the batch nature of productionof aligned carbon nanotubes the cost is still out of reach for manyapplications. Continuous or semi-continuous processes disclosed hereinaddresses the need for high volume production of aligned arrays.

The ability of the nanostructured material to have a wide-rangingdensity, for example ranging from 1 picogram/cm³ to 20 g/cm³, allowssuch material to be tailored for a wide variety of applications.Non-limiting examples of articles made from nanostructured material asdescribed herein include fabrics, filters, and structural supports. Dueto the highly desirable electrical, mechanical and thermal propertiesassociated with many carbon nanotubes, the creation of interlacednanostructured materials is possible. This interlacing would improve thestructural integrity of the nanostructured material over thosepreviously available, and would significantly improve the efficiency ofmechanical actuators, electrical wires, heat sinks, thermal conductors,or membranes for fluid purification.

Composite materials incorporating carbon nanotubes typically involveusing carbon nanotubes as an additive, in amounts often ranging from1-40 percent by weight. In many cases, such a loading of carbonnanotubes has improved performance properties of the final material atlower levels than other additives. While these compositions arewell-suited to many applications, their low addition levels of carbonnanotubes partially mask the carbon nanotube's extreme performancecharacteristics, especially their mechanical strength, thermal transferability, electrical conductivity, liquid sterilization capacity, andother high surface area effects.

The high strength associated with carbon nanotubes, about 100 times thetensile strength of steel at ⅙th the weight, allows the nanostructuredmaterial described herein to be used for puncture resistanceapplications, such as projectile bombardment or other ballisticmitigation applications. To further take advantage of the carbonnanotube's performance characteristics, it would be advantageous todesign and construct a mostly carbon nanotube one, two andthree-dimensional structure that has the inherent material strength tobe useful commercially. Further, a process that creates a one, two andthree-dimensional structure of interwoven carbon nanotubes in a simpleprocess would allow the material properties of this material to bereadily adjusted for strength, thickness, porosity, flexibility, andother properties. In particular, the nanostructured material describedherein exhibits excellent blast mitigation properties, which may bedefined in terms of energy adsorbed per unit impact area as a functionof the mass of the affected composite material.

Accordingly, creating materials, such as a cloth, composites andthreads, that comprises ultra-strong carbon nanotubes fused together toform a highly cross-linked network remains of high importance. Theproperties associated with such a material leads to a range ofbeneficial properties such as ultra-high tensile strength, low weight,acceptable flexibility, good thermal and electrical conductivity ideallysuited for air frames and space craft.

Furthermore, given the acute need for materials with thesecharacteristics in many applications there is a need for methods thatproduce these materials in a scaleable way. Accordingly, the presentdisclosure relates to a method for making surface grown carbon nanotubesin a more efficient way, and in higher volumes than currently availableand to using such nanotubes in the fabrication of nanostructuredmaterials or threads.

SUMMARY

The present disclosure is related to a continuous or semi-continuousmethod for producing a plurality of aligned carbon nanotubes, the methodcomprising depositing onto a moving or continuously moving substrate,

(1) a catalyst to initiate and maintain the growth of carbon nanotubes,and

(2) a carbon-bearing precursor, and

growing nanotubes inside of a chemical vapor deposition (CVD) reactor atconditions that promote the growth of substantially aligned carbonnanotubes on the catalyst support material.

In one embodiment, the carbon-bearing precursor is preheated by adelivery manifold prior to being introduced into the CVD reactor. Thecarbon-bearing precursors may be chosen from a variety of compound, suchas CH₄, C₂H₄, C₂H₂, CO₂, CO, and combinations thereof.

The movable or continuously moving substrate may comprise a flexibleribbon, ridged cylindrical, or ring, and may be made of a variety ofmaterials, such as metals, alloys and oxides. For example, the substratematerial may comprise platinum, palladium, iridium, iron, cobalt,nickel, chromium, carbon, silicon, aluminum, magnesium carbon,combinations, alloys or oxides thereof. It is understood that thesematerials may be found in the form of fibers, fabrics, mesh, sheets,wafers, cylinders, or plates.

The method according to one embodiment further comprises depositing acatalyst promotion material prior to depositing the catalyst material.In this embodiment, the catalyst may be exposed to catalyst promotionmaterial during carbon nanotube growth comprising. The catalystpromotion material may be chosen from sulfur, water vapor, hydrogen gas,deuterium gas, oxygen, fluorine, helium, argon, ammonium, nitrogen orcombinations thereof.

In one embodiment, depositing at least one of (1) the catalyst toinitiate and maintain the growth of carbon nanotubes, or (2) thecarbon-bearing precursor is performed using laminar flow conditions.Non-limiting examples of methods used to deposit the carbon bearingprecursor may be chosen from at least one technique chosen from chemicalvapor deposition, plasma enhanced chemical vapor deposition, physicalvapor deposition, plasma enhanced physical vapor deposition.

Additionally, the method may use an inert carrier gas for one of (1) or(2), such as argon, nitrogen, hydrogen, or any combination of suchgases. Alternatively, the carrier gas may comprise a pure gas, such aspure argon, nitrogen, or hydrogen.

The substrate on which the plurality of aligned carbon nanotubes isdeposited may be a flexible ribbon or ridged cylindrical material,comprised of a substance with sufficient thermally stability to survivethe temperature of the carbon-bearing precursor decomposition. In isunderstood that conditions that promote the growth of substantiallyaligned carbon nanotubes include a temperature ranging from 600 to 1,100degrees Celsius, and/or a carbon bearing precursor at a flow rate perunit substrate surface ranging from 10 ml/(cm² min) to 400 ml/(cm² min).

In one embodiment, the catalyst is comprised of iron, cobalt, nickel,platinum, lead, palladium, copper, gold, or any combination or alloythereof. While not required, such catalysts may comprise particleshaving diameter ranging from 0.7 nm and 50 nm.

It is also appreciated that carbon nanotubes made according to thepresent disclosure may have lengths ranging from 100 um to 20 cm. Thus,the continuously moving substrate may be moved at a speed sufficient toproduce these lengths.

In another non-limiting embodiment, there is disclosed a method forproducing substantially aligned carbon nanotubes, that comprisesdepositing onto a semi-continuous or continuously moving substrate:

(1) a catalyst to initiate and maintain the growth of carbon nanotubes,the catalyst comprising iron, cobalt, nickel, platinum, lead, palladium,copper, gold, or any combination or alloy thereof; and

(2) a carbon-bearing precursor at a flow rate per unit substrate surfaceranging from 10 ml/(cm² min) to 400 ml/(cm² min),

growing nanotubes inside of a chemical vapor deposition (CVD) reactor ata temperature ranging from 600 to 1,100 degrees Celsius.

It is understood that the substrate may comprise a flexible or rigidtape, wire, ribbon, cylindrical, or ring substrate of platinum,palladium, iridium, iron, cobalt, nickel, chromium, carbon, silicon,aluminum, magnesium carbon, combinations, alloys or oxides thereof.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a schematic of a system according to the present disclosureused to prepare a catalyst containing substrate.

FIG. 2. is a schematic of a system according to the present disclosureused to perform a continuous method for producing surface grown carbonnanotubes.

FIG. 3. is a schematic of a system according to the present disclosureused to perform a continuous method for producing surface grown carbonnanotubes via a laminar flow of gases to the growth substrate.

FIG. 4. is a schematic of a system according to the present disclosureused to perform a semi-continuous method for producing surface growncarbon nanotubes.

FIG. 5. is a schematic of a system according to the present disclosureused to perform a continuous method for growing, exfoliating andharvesting surface grown carbon nanotubes.

FIG. 6. is a schematic of a (a) side view of a system according to thepresent disclosure that uses a grow and weave method for the continuousgrowth of carbon nanotube containing material.

FIG. 7. is a schematic of a system according to the present disclosureused to perform a semi-continuous method for spinning surface growncarbon nanotubes into thread.

FIG. 8. is a schematic of a system according to the present disclosureused to perform a continuous method for producing and harvesting surfacegrown carbon nanotubes utilizing a single rotating drum.

FIG. 9. is a schematic of a system according to the present disclosureused to perform a continuous method for producing long or ultra-longcarbon nanotubes by re-depositing a catalyst on the opened ends of thetubes.

DETAILED DESCRIPTION OF THE INVENTION Definitions

The term “fiber” or any version thereof, is defined as an object oflength L and diameter D such that L is greater than D, wherein D is thediameter of the circle in which the cross section of the fiber isinscribed. In one embodiment, the aspect ratio LID (or shape factor) ofthe fibers used may range from 2:1 to 10⁹:1. Fibers used in the presentdisclosure may include materials comprised of one or many differentcompositions.

An “aligned array” refers to an arrangement of carbon nanotubes grown togive one or more desired directional characteristics. For example, analigned array of surface grown carbon nanotubes typically, but notexclusively, comprise random or ordered rows of carbon nanotubes grownsubstantially perpendicular to the growth substrate. An example of analigned array of carbon nanotubes is shown in FIG. 7. The commondirectional characteristic of such aligned arrays assist the carbonnanotubes in a subsequent fiber spinning process.

The prefix “nano-” (as in “carbon nanotubes”) refers to objects whichpossess at least one dimension that are on a nano-scale (e.g., onebillionth of a meter, 10⁻⁹ meters), such as on the atomic or molecularlevel. Nano-fiber will be known as a fiber whose diameter may be 0.4 nmto 500 nm. Carbon nanotubes described herein generally have an averagediameter in the inclusive range of from 1-200 nm and an average lengthin the inclusive range of from 20 nm and up.

The terms “nanostructured” and “nano-scaled” refers to a structure or amaterial which possesses components having at least one dimension thatis 100 nm or smaller. A definition for nanostructure is provided in ThePhysics and Chemistry of Materials, Joel I. Gersten and Frederick W.Smith, Wiley publishers, p382-383, which is herein incorporated byreference for this definition.

The phrase “nanostructured material” refers to a material whosecomponents have an arrangement that has at least one characteristiclength scale that is 100 nanometers or less. The phrase “characteristiclength scale” refers to a measure of the size of a pattern within thearrangement, such as but not limited to the characteristic diameter ofthe pores created within the structure, the interstitial distancebetween fibers or the distance between subsequent fiber crossings. Thismeasurement may also be done through the methods of applied mathematicssuch as principle component or spectral analysis that give multi-scaleinformation characterizing the length scales within the material.

The term “nanomesh” refers to a nanostructured material defined above,and that further is porous. For example, in one embodiment, a nanomeshmaterial is generally used as a filter media, and thus must be porous orpermeable to the fluid it is intended to purify.

The term “leading edge” refers to the carbon nanotubes growing while atthe edge of a forest where exfoliation from the surface is occurring.

“Defective carbon nanotubes” are those that contain a lattice distortionin at least one carbon ring. A lattice distortion means any distortionof the crystal lattice of carbon nanotube atoms forming the tubularsheet structure. Non-limiting examples include any displacements ofatoms because of inelastic deformation, or presence of 5 and/or 7 membercarbon rings, or chemical interaction followed by change in sp²hybridization of carbon atom bonds.

“Defective nano-fibers” are those that contain at least one latticedistortion along the crystalline structure of the nano-fiber.

An “impregnated carbon nanotube” is defined as a carbon nanotube thathas other atoms or clusters inserted inside of the carbon nanotube.

A “functionalized” carbon nanotube is defined as a carbon nanotube thathas bonded atoms or chemical groups to its surface.

A “doped carbon nanotube” is defined as a carbon nanotube that has thepresence of atoms of an element other than that which comprises themajority of the carbon nanotube, within the carbon nanotube crystallattice.

A “charged” carbon nanotube is defined as one that has a non-compensatedelectrical charge, in or on the surface of the carbon nanotube.

A “coated carbon nanotube” is defined as a carbon nanotube that issurrounded by or decorated with clusters of atoms other than that whichcomprises the majority of the carbon nanotube.

“Irradiated”, “irradiation” is defined as the bombardment of carbonnanotubes or the nano-structured material with any form of radiationsuch as, but not limited to, particles, molecules or photons (such asx-rays) of energy sufficient to cause inelastic deformation to thecrystal lattice of the carbon nanotube.

As used herein the term “fused,” “fusion,” or any version of the word“fuse” is defined as the bonding of carbon nanotubes at their point orpoints of contact. For example, such bonding can be Carbon-Carbonchemical bonding including sp³ hybridization or chemical bonding ofcarbon to other atoms.

As used herein the term “interlink,” “interlinked,” or any version ofthe word “link” is defined as the connecting of carbon nanotubes into alarger structure through mechanical, electrical or chemical forces. Forexample, such connecting can be due to the creation of a large,intertwined, knot-like structure that resists separation.

As used herein, “cross link”, “cross linked” or “cross linking” meansthat a chemical bond is formed between two or more nanotubes within thecarbon nanotube nanostructured material.

As used herein “catalyst poisoning” refers to the creation ofover-layers of carbon on the carbon nanotube catalyst therebyeliminating the ability of the catalyst to actively promote carbonnanotube formation. “Catalyst poisoning” can also refer to atoms ormolecules that adsorb into the catalyst and impend its nanotube growthfunction.

“Chosen from” or “selected from” as used herein refers to selection ofindividual components or the combination of two (or more) components.For example, the nano-structured material can comprise carbon nanotubesthat are only one of impregnated, functionalized, doped, charged,coated, and irradiated nanotubes, or a mixture of any or all of thesetypes of nanotubes such as a mixture of different treatments applied tothe nanotubes.

The following disclosure describes large-scale production methods forproducing nanostructured material. To that end, there is disclosed atleast one carbon nanotube species grown on or in at least one supportivematerial, with a force applied thereto, the force designed to form anano-cloth that has enhanced physical, chemical and/or electromechanicalproperties.

In one embodiment, the entire structure is put through at least oneiteration of at least one carbon nanotube species growth in thesupporting material with subsequent stretching of the material. Thisstretching may be accomplished by applying tension to the materialduring the growth or to the post grown aligned array of at least onecarbon nanotube species. Drawing the catalyst containing substrate undertension through the carbon nanotube growth zone has the advantage ofmaintaining intimate contact of the ribbon to the catalyst deliverymanifold to maintain the necessary temperature and pressure profile ofthe carbon containing precursor gas to the catalyst containingsubstrate.

Non-limiting examples of a supportive material can be fibers, spheres,or other shapes formed from materials comprising, but not limited to,carbon, glass, quartz, graphite, metals, ceramics, diamond, and othercommon materials.

Further embodiments of the invention are directed towards a one, two andthree-dimensional carbon nanotube structure composition formed fromcuring a structure, either chemically or physically, that is composedprimarily of at least one carbon nanotube species. Non-limiting examplesof curing methods are radiation, photochemical bonding, hightemperature, high current, laser absorption, laser heating, chemical, orpressure induced mechanical curing.

Certain embodiments of this invention are directed towards fusing theentire created structure using either chemical or physical methods. Forexample, such methods may include radiation from infrared and othersources sufficient enough to break apart covalent bonds in at least onecarbon nanotube species' structure and allow these broken covalent bondsto reform with nearby broken covalent bonds; photochemical bonding suchas, but not limited to, breaking the fullerene end-caps at the end ofthe at least one carbon nanotube species without breaking the morestable bonds within the body of the at least one carbon nanotube speciesand allow reformation of these broken bonds to nearby broken bonds; andlaser heating from such sources as, but not limited to, carbon dioxidelasers.

Further, non-limiting examples of these embodiments use bonding agentssuch as metals, ceramics, other carbon materials, and polymers. In theseembodiments, these materials may be added during carbon nanotubeconstruction or the carbon nanotubes may be treated or coated afterconstruction with at least one material comprising a metal, a polymericmaterial, and/or a ceramic material during or after the formation of thenanostructured material. These materials may be added to providespecific physical, chemical or electro-mechanical properties to thenanomaterial. In some embodiments, these materials are coated ondistinct layers of the overall material to form a polymer containinglayer, a ceramic containing layer, a metal containing layer, or acombination of any or all of these layers.

In some embodiments, the carbon nanotubes may take a form chosen fromhollow multi-walled carbon nanotubes, bamboo multi-walled carbonnanotubes, double-walled carbon nanotubes, single-walled carbonnanotubes, carbon nano-horns, carbon nano-spirals, carbon nanotubeY-junctions, or other carbon nanotube species.

The above described shapes are more particularly defined in M. S.Dresselhaus, G. Dresselhaus, and P. Avouris, eds. Carbon Nanotubes:Synthesis, Structure, Properties, and Applications, Topics in AppliedPhysics. Vol. 80. 2000, Springer-Verlag; and “A Chemical Route to CarbonNanoscrolls, L. M. Viculis, J. J. Mack, and R. B. Kaner; Science 28 Feb.2003; 299, both of which are herein incorporated by reference.

In one aspect of the invention, due to the controlling the formationconditions of the components of the nanostructured material, theresulting structure may comprise 5, 6 and 7-membered carbon rings at theintersection of two or more carbon nanotubes. These different ringstructures can lead to distortions in the carbon nanotubes, which tendto aid in the formation of a self-assembling nanostructured material.

In any of the above-described methods, the starting carbon nanotubesgenerally contain residual catalytic particles that remain afterproduction of the nanotubes. In certain embodiments, it may be desiredto treat the carbon nanotube material with a strong oxidizing agent suchas acids and/or peroxides or combinations thereof in order to remove thecatalytic particle impurities.

Some embodiments use bonding agents such as metals, ceramics, othercarbon materials, and polymers to improve the physical, chemical and/orelectro-mechanical properties of the nano-material. The polymers,ceramics, and/or metals, which may be included in the nano-material, maybe in a form chosen from fibers, beads, particles, wires, sheets, foils,and combinations thereof. In these particular embodiments, the agentsare added after the construction of the carbon nanotube material bytreating, coating or by using layer by layer techniques with at leastone material comprising a metal, a polymeric material, a ceramicmaterial, carbon fiber, carbon nanotubes, diamond, activated carbon,graphite, poly-electrolytes or other carbon material common to the artduring or after the formation of the nanostructured material.

Non-limiting examples of polymers that can be used in the nanostructuredmaterial described herein are chosen from single or multi-componentpolymers including nylon, acrylic, methacrylic, epoxy, silicone rubbers,natural rubbers, synthetic rubbers, vulcanized rubbers, polypropylene,polyurethane, polycarbonates, polyethylene, aramids (i.e. KevJar® andNomex®), polystyrene, polychloroprene, polybutylene terephthalate,poly-paraphylene terephtalamide, polyesters [e.g. poly(ethyleneterephthalate), such as Dacron®], polyester ester ketone,polytetrafluoroethylene (i.e. Teflon®), polyvinyl acetate, poly(p-phenylene terephtalamide), polyvinylchloride, viton fluoroelastomer,polymethyl methacrylate (i.e. Plexiglass®), and polyacrylonitrile (i.e.Orlon®), and any combination thereof

Non-limiting examples of ceramics, ceramic-like, and other materialsthat can be used in the nanostructured material described hereininclude: silicon oxide, silicon nitride, silicon carbide, titaniumoxide, titanium carbide, titanium nitride, titanium boride, magnesiumoxide, boron carbide, boron nitride, zirconium oxide, zirconium carbide,zirconium boride, zirconium nitride, aluminum oxide, alumina, aluminumnitride, aluminum hydroxide, scandium oxide, hafnium oxide, hafniumboride, yttrium oxide, thorium oxide, cerium oxide, spinel, garnet,lanthanum fluoride, calcium fluoride, quartz, carbon and its allotropes,cordierite, mullite, glass, silicon nitride, ferrite, steatite, orcombinations thereof.

Non-limiting examples of metals may be chosen antimony, arsenic,aluminum, selenium, zinc, gold, silver, copper, platinum, palladium,boron, nickel, iridium, rhodium, cobalt, osmium, ruthenium, iron,manganese, molybdenum, tungsten, zirconium, titanium, gallium, indium,cesium, chromium, gallium, cadmium, strontium, rubidium, barium,beryllium, tungsten, mercury, uranium, plutonium, thorium, lithium,sodium, potassium, calcium, niobium, magnesium, tantalum, silicon,germanium, tin, lead, or bismuth, yttrium, their oxides, hydrides,hydroxides, salts or any alloys thereof.

In this embodiment the metal may be deposited using traditional chemicalmethods or chemical or physical vapor deposition methods. Non-limitingexamples of traditional chemical methods are salt decomposition,electrolysis coating, electro-coating, precipitation, and colloidalchemistry. Non-limiting examples of chemical or physical vapordeposition methods are metal organic chemical vapor deposition, electronsputtering, thermal sputtering, and/or plasma sputtering.

In one embodiment, at least one of the previously described polymers,ceramics, and metals are coated on the surface of the carbon nanotubesto form a polymer containing layer, a ceramic containing layer, a metalcontaining layer, or a combination of any or all of these layers.

Non-limiting examples of polymeric coatings added after construction ofthe nanomaterial are nitrocellulose, formaldehyde, melamine, epoxy,polyurethane, acrylic, urea, silicon, or combinations thereof. Furthernon-limiting examples of polymeric materials are polymeric linkagescreated by functional groups on the at least one carbon nanotubesurface. Non-limiting examples of functional groups are carboxyl,amino-, chloro-, bromo-, fluoro-, epoxy-, isocyano-, thio-, or otherpolymeric linkages common to the art.

In some embodiments, other nanostructured fibers particles and/or othernano-scale particles may be added during nanomaterial formation toprovide specific behaviors to the resulting nanomaterial. For example,quantum dots may be utilized to adjust and/or control the spectralabsorption, reflection and emission characteristics of the nanomaterialfor signature management applications.

It is possible, and in some circumstances desirable, to make a monolayerof carbon nanotube fabric. Alternatively, it is desirable to make athree dimensional nanostructured material using a sequence of processingsteps to produce a woven carbon nanotube fabric. One non-limitingexample of a sequence would be:

(1) depositing a sacrificial substrate onto the first sector of a slowlyrotating drum;

(2) applying nano-particles of a catalyst, such as iron, to thesubstrate to initiate carbon nanotube growth;

(3) growing, using for example, a Chemical Vapor Deposition (CVD) orPhysical Vapor Deposition (PVD) process, a quasi-two dimensional mat ofvertically-aligned carbon nanotubes. The length of these carbonnanotubes being controlled by the rotation rate of the drum, thetemperature, pressure and the input rate of the feedstock gas; and

(4) exfoliating the woven nanotube material/sacrificial substrate fromthe drum and feeding the exfoliated material as a continuous sheet intolater stages of the fabric manufacturing device for post processing.

In this type of method, growing of the carbon nanotubes comprises theChemical Vapor Deposition or Physical Vapor Deposition of catalyst. Theprocess of applying the catalyst may comprise depositing a metal-organiccatalyst layer, such as ferrocene or an iron pentacarbonyl containinglayer. The process to grow carbon nanotubes typically requires afeedstock gas containing vapor to be in the presence of catalystnano-particles at a temperature sufficient to produce carbon nanotubegrowth.

As shown in FIG. 1, one embodiment of the present disclosure is directedto treating the deposition substrate prior to growing carbon nanotubes.In this embodiment, the substrate may initially be heated, such as withan infrared lamp, to remove contaminants followed by depositing acatalyst support, such as a silicon oxide, prior to depositing thecatalyst. It is appreciated that the atmosphere may be controlleddepending on the type of deposition methods used for the catalystsupport and catalyst. For example, when a chemical or physical vapordeposition method is used, the system can be exposed to a vacuum orultra high vacuum.

In another embodiment, the method comprises a continuous method ofmaking a one, two and three-dimensional nanostructured material, themethod comprising:

(1) growing carbon nanotubes in situ;

(2) applying tension to direct the growth of the carbon nanotubes;

(3) interweaving the grown carbon nanotubes subsequent to the growingprocess and reeling them onto a spool; and

(4) treating the woven material, such as by fusing, annealing, chemicalvapor deposition of materials onto the surface of the nanostructurednano-fiber material, physical vapor deposition of materials onto thesurface of the nanostructured nano-fiber material, spraying, and/orpressing, to add specific performance characteristics to thenanomaterial.

With reference to FIG. 2, a continuous method for producing surfacegrown carbon nanotubes may employ a thermally conductive manifold forthe laminar flow of the carbon precursor. This embodiment employs arotating belt that permits treating of the deposition substrate (e.g., aplatinum ribbon, carbon nanotube paper, or segmented plates of metal orquartz that have been joined to form a continuous belt) beforedepositing carbon nanotubes thereon. Treating the substrate may includea plasma etch or chemical clean to clean the surface prior to depositinga catalyst support, which may include an oxide of aluminum, silicon, andtitanium. This embodiment further includes a exfoliation system, such asa blade, to remove the surface grown carbon nanotube from the substrate,as well as a container for collecting the exfoliated carbon nanotubes.

FIGS. 3 and 4 also show various systems for the continuous growth ofcarbon nanotubes using a different method that leads to a differentproduct than that described in FIG. 2. For example, unlike FIG. 2, thisembodiment utilizes a substrate (in these embodiments, carbon nanotubes)that already contains a catalyst and that will become an integral partof the finished product. Accordingly, a system according to theseembodiments do not require a separate pre-treatment/catalyst depositionzone. Also, the system employs a take-up reel or mandrel for spoolingthe as-grown nanostructured material, rather than an exfoliation system,as used in FIG. 2.

FIG. 5 shows another inventive embodiment for the continuous growth ofcarbon nanotubes. This embodiment also uses an exfoliation system toremove the surface grown carbon nanotubes from the growth substrate, butwhich enables the carbon nanotubes to be gathered on a spool or mandrelas a continuous material, rather than as separate clusters.

It is appreciated that in any of the disclosed embodiments, the inputrate of the feedstock gas and the reaction conditions may be preciselycontrolled, to a level previously unattainable, to direct the growth ofthe carbon nanotubes. In addition, either during or after a growthphase, directed tension may be applied to the forming carbon nanotubesto control their positions. Through this directed growth, a nano-weavingprocess may be enabled that allows for the creation of an ultra-highstrength, woven nanomaterial.

As described, one beneficial aspect of the invention is the continuousnature of the production of aligned carbon nanotubes through themechanical movement of catalyst through the carbon nanotube growth zone.This extremely precise control of all of the environmental and growthparameters enable the repeated fabrication of a highly reproduciblematerial.

Another embodiment, which is illustrated in FIG. 6, is directed to acontinuous method for making a one, two and three-dimensionalnanostructured material comprising:

(1) depositing a movable or moving catalyst onto a substrate, such as asmooth substrate;

(2) moving the catalyst containing substrate into a carbon nanotubegrowth zone of a reactor to continually expose fresh catalyst to carboncontaining precursor;

(3) growing carbon nanotubes from the catalyst;

(4) optionally applying sufficient tension to the woven sheet of carbonnanotubes at the leading edge to remove from the substrate; and

(5) treating the woven sheet, such as fusing, annealing, chemical vapordeposition of materials onto the surface of the nanostructurednano-fiber material, physical vapor deposition of materials onto thesurface of the nanostructured nano-fiber material, spraying, and/orpressing, to add specific performance characteristics to thenano-material.

In another embodiment, the mechanical action of the carbon nanotubesremoval from the growth substrate is performed slowly enough to deliversufficient tension to cause the carbon nanotubes to grow longer beforethe carbon nanotubes come completely free from the growth substrate. Thenext row of carbon nanotubes will grab the row that was just removed dueto van der Wals forces. The harvested nanotubes are aligned in-planewith the newly formed ribbon in near monolayer thickness. Materials maybe deposited onto this thin near monolayer of carbon nanotubes.

In another embodiment, the thin film or spun fibers of carbon nanotubesare drawn from and simultaneously coated or functionalized from theas-produced ribbon of carbon nanotubes. As shown in FIG. 7, the coatingor functionalization maybe accomplished with a physical vapor depositionprocess, or chemical ion deposition. Materials such as nickel and otherlattices matching materials can form strong mechanical bonding to thegraphene surface of a carbon nanotube. A carbon nanotube wire that isclad in metal is easily bonded to other metallic structures. Byfunctionalizing the carbon nanotubes it is possible to crosslink themtogether with covalent bonding for enhanced strength. It is advantageousto accomplish post processing of the aligned array of carbon nanotubesprior to the exposure of the carbon nanotubes to atmosphericcontaminates such as oxygen because oxygen in known to damage carbonnanotubes at elevated temperatures.

In certain embodiments of the present disclosure, the substrate maycomprise a drum. For example, FIG. 8 shows a system similar to FIG. 2for cleaning the surface prior to depositing a catalyst support,depositing oxide and catalyst except that a rotating,temperature-controlled drum is used instead of a belt.

The deposition substrate comprising a drum may be used to fabricate longor ultra-long carbon nanotubes. For example, FIG. 9 shows a rotatingdrum method for growing long carbon nanotubes by re-depositing thecatalyst on the opened ends of the tubes, such as in the sublayer of thecarbon nanotubes, and subsequently continuing growth of each tube. Oneoptional embodiment of this method is directed to depositing a catalystsupport layer in the form of an oxide and growing a “jelly roll”structure that can be removed from the drum at a later time.

In another embodiment the as-produced ribbon of carbon nanotubes mayalso be used as a contamination free growth substrate for a secondary ortertiary arrays of carbon nanotubes.

Further embodiments of the present invention are directed to methods forimproving the material properties of a one, two and three-dimensionalcarbon nanotube structure, such as, but not limited to, physical andchemical curing methods. It will be apparent to one of ordinary skill inthe art that certain embodiments of the present invention may bedirected to some or all of these aspects of the present invention aswell as other desirable aspects.

Because of the fine control over the design of the nano-structuredmaterial facilitated by the inventive method, a myriad of applicationsbecome possible. The ability to precisely control the location andnature of added functional chemical groups on individual carbonnanotubes along with the ability to interlace carbon nanotubes ofdiffering chemical and physical composition allows for the creation ofnano-fabrics with very specific physical properties that bond withspecific chemical species.

Applications that require materials with specific physical propertieswill benefit from this invention. These include protective clothing(e.g. both ballistic and chemical agent protection, materialreinforcement), actuators and motion control sensors (e.g. forcesensitive fabrics), ultra-strength composites, high efficiencyelectrical devices (e.g. electrically conductive materials, thermallyconductive materials, cold cathodes), energy applications (e.g.high-efficiency storage devices including batteries andsuper-capacitors, high-efficiency transmission, high magnetic fieldmagnets).

Further, materials made according to the present disclosure can be usedin applications that include any type of contaminant removal. Theseinclude particle containment, fluid filtration, fluid sterilization,desalinization, molecular sorting, pharmaceutical processing, petroleumrefining, reusable gas super-absorbents, catalytic substrates.

In addition, there is described a device made from aligned carbonnanotubes or materials containing aligned carbon nanotubes madeaccording to the disclosed method. For example, in one embodiment, thereis disclosed micro-devices or nano-devices include but are not limitedto embedded solar cells, light emitting diodes, diodes, rectifiers,amplifiers, transistors, resisters, capacitors, inductors, lenses,reflectors, lasers, optical switches, electrical switches, batteries,antennae, integrated circuits, mass storage devices, sensors,micro-electro-mechanical systems (MEMS), nano-electro-mechanical systems(NEMS).

In one embodiment, the carbon nanotube material may be fabricated suchthat the described micro-devices or nano-devices are integrated togetherfor the purpose of mechanically responding, transmitting power,transmitting information, transporting materials, transporting heat orany combination thereof.

In one aspect of the present disclosure, the nanostructured materialcomprises defective carbon nanotubes chosen from impregnated,functionalized, doped, charged, and/or irradiated. Such carbon nanotubesmay be bound together or with other “support” materials.

In some embodiments, added support materials may be used to support thefabrication of the one, two and three-dimensional structure and/or maybecome an integral part of the structure. Alternatively, these materialsmay be sacrificial, meaning that they are removed by subsequentprocessing, such as thermal or chemical procedures, to eliminate themfrom the final structure, while leaving a stable structure comprisedalmost entirely of carbon nanotubes. The sacrificial support materialmay be used to assist in the exfoliation of the nanomaterial duringproduction and/or may be used in applications that do not require theproperties of the support material in the final product, such as incertain high strength or armor/ballistic applications, but may need itduring production.

In any of the previously described methods, the carbon nanotubes may begrown with high temperature and/or high pressure bathing of a feedstockgas chosen from but not limited to: ethanol, carbon monoxide, carbondioxide, xylene, acetylene, methane, ethane, supercritical noble gases,supercritical phases of metal-organics and metal-inorganics, andsupercritical organo-silanes. Growth of the carbon nanotubes may beenhanced and controlled by depositing a metal-organic catalyst layer,such as ferrocene or iron pentacarbonyl.

In one non-limiting embodiment, the method could comprise the chemicalor physical vapor deposition of at least one material chosen frompreviously described ceramics, metals, and polymers. During this method,deposition comprises the depositing of at least one of the previouslydescribed polymers, ceramics, and metals near the intersecting points ofcarbon nanotubes within the nano-structured material.

In addition, fusing of the materials within the nanomaterial may beperformed by irradiative, electrical, chemical, thermal, or mechanicalprocessing, either independently or in conjunction with one another. Forexample, irradiative processing may comprise e-beam irradiation, UVradiation, X-ray, gamma ray, beta radiation, and ionizing radiation.Chemical processing may comprise treating the carbon nanotubes with atleast one material chosen from acids, bases, peroxides, and amines for atime sufficient to facilitate fusion of the carbon nanotubes with oneanother. Similarly, chemical processing may comprise photochemicalbonding for a time sufficient to obtain chemical cross linking.

When fusing occurs through a mechanical process, it can be done througha mechanical pressing of a carbon nanotube intersection with sufficientpressure to cause at least two nano-fibers to bond. According to amethod described herein, the one, two and three-dimensionalnanostructured material may be thermally or electromagnetically annealedto add further benefits to the structure, such as structural integrity.For example, by passing a current through or by creating eddy currentsthrough electromagnetic field immersion one can cause electro-migrationin an amount sufficient to fuse nanotubes together, which, depending onthe particular conditions (including field strength, and nanotubemorphology) can lead not only to the modification of such defects, butcan cause defect creation, elimination or migration.

Any or all of the above-described methods can be further generalized toconstruct a multi-layered nanomesh material wherein each layer may be ofthe same or different composition from other layers within the layeredmaterial. Further, each layer may be specifically designed to providesome desired behavior to the resulting multi-layer material. Inaddition, some of these layers may include layers not composed ofnano-material and whose presence provides mechanical, electrical, and/orthermal properties or acts to set inter-membrane spacing for thenanomesh layers.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present invention.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

What is claimed:
 1. A method for producing substantially aligned carbonnanotubes, said method comprising depositing onto a continuously movingsubstrate, (1) a catalyst to initiate and maintain the growth of carbonnanotubes, and (2) a carbon-bearing precursor, growing nanotubes insideof a chemical vapor deposition (CVD) reactor at conditions that promotethe growth of substantially aligned carbon nanotubes on the catalystsupport material.
 2. The method of claim 1, wherein the carbon-bearingprecursor is preheated by a delivery manifold prior to being introducedinto the CVD reactor.
 3. The method of claim 1, wherein saidcontinuously moving substrate is a flexible ribbon, ridged cylindrical,or ring.
 4. The method of claim 1, wherein the moving substratecomprises platinum, palladium, iridium, iron, cobalt, nickel, chromium,carbon, silicon, aluminum, magnesium carbon, combinations, alloys oroxides thereof.
 5. The method of claim 1, wherein said moving substratecomprises fibers, fabrics, mesh, sheets, wafers, cylinders, or ringplates.
 6. The method of claim 1, further comprising depositing acatalyst promotion material prior to depositing said catalyst material.7. The method of claim 6, wherein the catalyst promotion materialcomprises sulfur, water vapor, hydrogen gas, deuterium gas, oxygen,fluorine, helium, argon, ammonium, nitrogen or combinations thereof. 8.The method of claim 1, wherein said depositing at least one of (1) or(2) is performed using laminar flow conditions.
 10. The method of claim1, wherein the carbon-bearing precursors is comprised of CH₄, C₂H₄,C₂H₂, CO₂, CO, or combinations thereof.
 11. The method of claim 1,wherein said CVD reactor includes at least one technique chosen from,plasma, physical vapor deposition, electromagnetic fields, orcombinations thereof.
 13. The method of claim 1, wherein thesubstantially aligned carbon nanotubes are comprised of hollowmulti-walled nanotubes, bamboo multi-walled nanotubes, double-wallednanotubes, single-walled nanotubes, nano-spirals, and any combinationthereof.
 14. The method of claim 1, wherein said substantially alignedcarbon nanotubes form at least a monolayer of carbon nanotubes.
 15. Themethod of claim 1, wherein said conditions that promote the growth ofsubstantially aligned carbon nanotubes include a temperature rangingfrom 600 to 1,100 degrees Celsius.
 16. The method of claim 1, whereinsaid conditions that promote the growth of substantially aligned carbonnanotubes include the deposition of carbon bearing precursor at a flowrate per unit substrate surface ranging from 10 ml/(cm² min) to 400ml/(cm² min).
 17. The method of claim 1, wherein said catalyst iscomprised of iron, cobalt, nickel, platinum, lead, palladium, copper,gold, or any combination or alloy thereof.
 18. The method of claim 1,wherein said catalyst comprises a particle having diameter ranging from0.7 nm and 50 nm.
 19. The method of claim 1, wherein said continuouslymoving substrate is moving at a speed sufficient to produce said carbonnanotubes to a length ranging from 100 um to 20 cm.
 20. A method forproducing substantially aligned carbon nanotubes, said method comprisingdepositing onto a semi-continuous or continuously moving substrate: (1)a catalyst to initiate and maintain the growth of carbon nanotubes, saidcatalyst comprising iron, cobalt, nickel, platinum, lead, palladium,copper, gold, or any combination or alloy thereof; and (2) acarbon-bearing precursor at a flow rate per unit substrate surfaceranging from 10 ml/(cm² min) to 400 ml/(cm² min), growing nanotubesinside of a chemical vapor deposition (CVD) reactor at a temperatureranging from 600 to 1,100 degrees Celsius, wherein said substratecomprises a flexible or rigid tape, wire, ribbon, cylindrical, or ringsubstrate of platinum, palladium, iridium, iron, cobalt, nickel,chromium, carbon, silicon, aluminum, magnesium carbon, combinations,alloys or oxides thereof.